It is desirable to increase polyunsaturated fatty acid (PUFA) content of milk to help increase the dietary intake of these beneficial fatty acids. For example, omega-3 unsaturated fatty acids are recognized as important dietary compounds for preventing arteriosclerosis and coronary heart disease, for alleviating inflammatory conditions and for retarding the growth of tumor cells. For children, it would also be desirable to increase both the omega-3 (especially DHA, C22:6n-3) and the omega-6 fatty acid content of milk as the eicosanoids from the omega-6 fatty acids are important for growth and DHA is important in brain and nervous system development. Milk is not only an important food source in its own right, but it can also be used to make a wide variety of other dairy products, such as butter, yogurt, cheese and the like.
One way to enrich omega-3 and omega-6 PUFAs in milk is to increase the content of these fatty acids in the feed ration of ruminants. However, it has been found that ruminants fed high concentrations of long chain unsaturated fat in their feed rations can sometimes exhibit one or more of the following results: (1) reduced milk output; (2) decreased fat content in the milk; (3) decreased protein content in the milk; and (4) increased trans-fatty acid content in the milk.
Accordingly, it would be desirable to have improved methods of producing PUFA-enriched milk. The present invention satisfies this desire and provides related advantages as well.